How to model those stylized trunks (See image)
I think the best way to achieve trees with branches is to make use of the Skin Modifier.
Begin by enabling a couple of add-ons (&quot;Extra Objects&quot;), if they're not already enabled.

This will give you the ability to add a single vert from the mesh menu.

Add a vertex, and give it a Skin Modifier.

You can extrude points by selecting them and then Ctrl + Right Click somewhere else (where you want to extrude it to). You can then scale the individual points using Ctrl + A.

You can also reselect individual points and extrude them elsewhere to make multiple &quot;branches&quot;

Once you have the tree shape you like, you can add a Subdivision Surface Modifier to make it smooth and round.

The best thing about this method, I find, is that it makes proper &quot;knuckles&quot; where the different branches connect to each other.